const loview = {
	window.requestAnimFrame = function () {
	  return (
	    window.requestAnimationFrame ||
	    window.webkitRequestAnimationFrame ||
	    window.mozRequestAnimationFrame ||
	    window.oRequestAnimationFrame ||
	    window.msRequestAnimationFrame ||
	    function (callback) {
	      window.setTimeout(callback);
	    }
	  );
	};
	
	function init(elemid) {
	  let canvas = document.getElementById(elemid),
	    c = canvas.getContext("2d"),
	    w = (canvas.width = window.innerWidth),
	    h = (canvas.height = window.innerHeight);
	  c.fillStyle = "rgba(30,30,30,1)";
	  c.fillRect(0, 0, w, h);
	  return { c: c, canvas: canvas };
	}
	
	window.onload = function () {
	  let c = init("canvas").c,
	    canvas = init("canvas").canvas,
	    w = (canvas.width = window.innerWidth),
	    h = (canvas.height = window.innerHeight),
	    mouse = { x: false, y: false },
	    last_mouse = {};
	
	  //initiation
	
	  function dist(p1x, p1y, p2x, p2y) {
	    return Math.sqrt(Math.pow(p2x - p1x, 2) + Math.pow(p2y - p1y, 2));
	  }
	
	  class segment {
	    constructor(parent, l, a, first) {
	      this.first = first;
	      if (first) {
	        this.pos = {
	          x: parent.x,
	          y: parent.y,
	        };
	      } else {
	        this.pos = {
	          x: parent.nextPos.x,
	          y: parent.nextPos.y,
	        };
	      }
	      this.l = l;
	      this.ang = a;
	      this.nextPos = {
	        x: this.pos.x + this.l * Math.cos(this.ang),
	        y: this.pos.y + this.l * Math.sin(this.ang),
	      };
	    }
	    update(t) {
	      this.ang = Math.atan2(t.y - this.pos.y, t.x - this.pos.x);
	      this.pos.x = t.x + this.l * Math.cos(this.ang - Math.PI);
	      this.pos.y = t.y + this.l * Math.sin(this.ang - Math.PI);
	      this.nextPos.x = this.pos.x + this.l * Math.cos(this.ang);
	      this.nextPos.y = this.pos.y + this.l * Math.sin(this.ang);
	    }
	    fallback(t) {
	      this.pos.x = t.x;
	      this.pos.y = t.y;
	      this.nextPos.x = this.pos.x + this.l * Math.cos(this.ang);
	      this.nextPos.y = this.pos.y + this.l * Math.sin(this.ang);
	    }
	    show() {
	      c.lineTo(this.nextPos.x, this.nextPos.y);
	    }
	  }
	
	  class tentacle {
	    constructor(x, y, l, n, a) {
	      this.x = x;
	      this.y = y;
	      this.l = l;
	      this.n = n;
	      this.t = {};
	      this.rand = Math.random();
	      this.segments = [new segment(this, this.l / this.n, 0, true)];
	      for (let i = 1; i < this.n; i++) {
	        this.segments.push(
	          new segment(this.segments[i - 1], this.l / this.n, 0, false)
	        );
	      }
	    }
	    move(last_target, target) {
	      this.angle = Math.atan2(target.y - this.y, target.x - this.x);
	      this.dt = dist(last_target.x, last_target.y, target.x, target.y) + 5;
	      this.t = {
	        x: target.x - 0.8 * this.dt * Math.cos(this.angle),
	        y: target.y - 0.8 * this.dt * Math.sin(this.angle),
	      };
	      //update first segment to follow target
	      if (this.t.x) {
	        this.segments[this.n - 1].update(this.t);
	      } else {
	        this.segments[this.n - 1].update(target);
	      }
	      for (let i = this.n - 2; i >= 0; i--) {
	        //update rest to follow segment in front of current segment
	        this.segments[i].update(this.segments[i + 1].pos);
	      }
	      if (
	        dist(this.x, this.y, target.x, target.y) <=
	        this.l + dist(last_target.x, last_target.y, target.x, target.y)
	      ) {
	        this.segments[0].fallback({ x: this.x, y: this.y });
	        for (let i = 1; i < this.n; i++) {
	          this.segments[i].fallback(this.segments[i - 1].nextPos);
	        }
	      }
	    }
	    show(target) {
	      if (dist(this.x, this.y, target.x, target.y) <= this.l) {
	        c.globalCompositeOperation = "lighter";
	        c.beginPath();
	        c.lineTo(this.x, this.y);
	        for (let i = 0; i < this.n; i++) {
	          this.segments[i].show();
	        }
	        c.strokeStyle =
	          "hsl(" +
	          (this.rand * 60 + 180) +
	          ",100%," +
	          (this.rand * 60 + 25) +
	          "%)";
	        c.lineWidth = this.rand * 2;
	        c.lineCap = "round";
	        c.lineJoin = "round";
	        c.stroke();
	        c.globalCompositeOperation = "source-over";
	      }
	    }
	    show2(target) {
	      c.beginPath();
	      if (dist(this.x, this.y, target.x, target.y) <= this.l) {
	        c.arc(this.x, this.y, 2 * this.rand + 1, 0, 2 * Math.PI);
	        c.fillStyle = "white";
	      } else {
	        c.arc(this.x, this.y, this.rand * 2, 0, 2 * Math.PI);
	        c.fillStyle = "darkcyan";
	      }
	      c.fill();
	    }
	  }
	
	  let maxl = 300,
	    minl = 50,
	    n = 30,
	    numt = 500,
	    tent = [],
	    clicked = false,
	    target = { x: 0, y: 0 },
	    last_target = {},
	    t = 0,
	    q = 10;
	
	  for (let i = 0; i < numt; i++) {
	    tent.push(
	      new tentacle(
	        Math.random() * w,
	        Math.random() * h,
	        Math.random() * (maxl - minl) + minl,
	        n,
	        Math.random() * 2 * Math.PI
	      )
	    );
	  }
	  function draw() {
	    //animation
	    if (mouse.x) {
	      target.errx = mouse.x - target.x;
	      target.erry = mouse.y - target.y;
	    } else {
	      target.errx =
	        w / 2 +
	        ((h / 2 - q) * Math.sqrt(2) * Math.cos(t)) /
	          (Math.pow(Math.sin(t), 2) + 1) -
	        target.x;
	      target.erry =
	        h / 2 +
	        ((h / 2 - q) * Math.sqrt(2) * Math.cos(t) * Math.sin(t)) /
	          (Math.pow(Math.sin(t), 2) + 1) -
	        target.y;
	    }
	
	    target.x += target.errx / 10;
	    target.y += target.erry / 10;
	
	    t += 0.01;
	
	    c.beginPath();
	    c.arc(
	      target.x,
	      target.y,
	      dist(last_target.x, last_target.y, target.x, target.y) + 5,
	      0,
	      2 * Math.PI
	    );
	    c.fillStyle = "hsl(210,100%,80%)";
	    c.fill();
	
	    for (i = 0; i < numt; i++) {
	      tent[i].move(last_target, target);
	      tent[i].show2(target);
	    }
	    for (i = 0; i < numt; i++) {
	      tent[i].show(target);
	    }
	    last_target.x = target.x;
	    last_target.y = target.y;
	  }
	
	  canvas.addEventListener(
	    "mousemove",
	    function (e) {
	      last_mouse.x = mouse.x;
	      last_mouse.y = mouse.y;
	
	      mouse.x = e.pageX - this.offsetLeft;
	      mouse.y = e.pageY - this.offsetTop;
	    },
	    false
	  );
	
	  canvas.addEventListener("mouseleave", function (e) {
	    mouse.x = false;
	    mouse.y = false;
	  });
	
	  canvas.addEventListener(
	    "mousedown",
	    function (e) {
	      clicked = true;
	    },
	    false
	  );
	
	  canvas.addEventListener(
	    "mouseup",
	    function (e) {
	      clicked = false;
	    },
	    false
	  );
	
	  function loop() {
	    window.requestAnimFrame(loop);
	    c.clearRect(0, 0, w, h);
	    draw();
	  }
	
	  window.addEventListener("resize", function () {
	    (w = canvas.width = window.innerWidth),
	      (h = canvas.height = window.innerHeight);
	    loop();
	  });
	
	  loop();
	  setInterval(loop, 1000 / 60);
	};
}


export default loview